He said that while flying home, he was looking at the sky while everyone was sound asleep and he heard a voice

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Philippines President Rodrigo Duterte makes a speech during the Philippines - China Trade and Investment Fourm at the Great Hall of the People on Oct. 20, 2016, in Beijing, China. Duterte has avowed cursing after he claims hearing a voice from a perceived god.

The foul-mouthed Philippine president, who once called the pope a "son of a bitch" and told Barack Obama to "go to hell," says he has promised to God he won't spew expletives again.

President Rodrigo Duterte's profanities have become a trademark of his political persona, especially when threatening to kill drugs dealers as part of his war on illegal drugs that has left thousands dead since he took office at the end of June.